Amateur Radio RF Environment Evaluation Exemption Calculator Optional Information Enter Frequency in MHz Calculated Minimum Distance Required (Feet) Enter Distance to Antenna (Feet) Note: Minimun Distance 7.87" Calculated - Does Exemption Apply? Select Coax Type Belden 8237 RG-8 Belden 9913 RG-8 Belden 9258 RG-8X Belden 9201 RG-58 Belden 8267 RG-213/U Times LMR-400 Enter Length of Coax in feet Enter Transmitter Power in Watts Select dBi or dBd and Enter Antenna Gain dBi dBd Calculated - Effective Radiated Power (ERP) (Watts) Calculated - Maximum Allowed ERP (Watts) The Amateur Radio RF Environment Exemption Calculator determines if the FCC Exemption to Routine Evaluation applies. It also calculates the maximum allowed Effective Radiated Power (ERP). Enter the frequency and distance to the antenna. If the calculator indicates that the exemption applies, select the type of coaxial cable, enter the cable length, transmitter power and antenna gain. The calculator displays the station's ERP and the maxium allowed power.  Adjust transmitter power may be adjusted to keep the station's ERP below the maximum allowed. Note: Stations, not qualifying for an exemption, may still meet the FCC Maximum Permissible Exposure (MPE) limits by perfoming a RF environmental analysis.  A suggested resource, with more information is: www.arrl.org/rf-exposure. Calculation formulas: The exemption applies if, R, the distance between the antenna and human exposure (meters) is greater than the wavelength/2π.  The maximum allowed ERP is determined by the adjacent formulas, where "f" is frequency (MHz). Frequency (MHz) Maximum ERP (Watts) 0.3 - 1.34 1,920 * R^2 1.34 - 30 3,450 * R^2 / f^2 30 - 300 3.83 / R^2 300 - 1,500 0.0128 * R^2 *f 1,500 - 100,000 19.2 * R^2 This calculator is being made available in support of Amateur Radio activities. The author assumes no liability or responsibilities for errors or omissions. Rev 3.7  Authored by KA6UGS.  For questions email: [email protected]